The present invention relates to an immunopotentiator and a method of modifying a water-soluble polysaccharide of a plant tissue material such as a Poaceae plant and particularly rice bran using an enzyme complex produced by the Hyphomytes so as to obtain the immunopotentiator.
Immunopotentiators have a variety of applications as foodstuffs and drugs. It is known that aging and stress lower the animal immunity and as such we easily suffer from various diseases. A new branch of nutritional chemistry which tries to fortify human immunity by improving the daily diet is in a new stage of development in consideration of the importance of preventive medicine. In a cancer therapy, the use of an immunopotentiator with a chemotherapeutic drug and radiotherapy has demonstrated an excellent therapeutic effect.
The present inventor found effectiveness of modification of a natural material using the Hyphomytes in developing and activating natural killer cells (NK cells) in the human immune system.
There is already known a method of metabolizing a natural material, i.e., a plant fiber material in a culture solution (Japanese Patent Laid-Open No. 1-153701). In this prior art, rice bran is used as the material. The rice bran is degreased and denigninized and is treated with a low-concentration alkali, thereby producing rice bran crude hemicellulose. By using this substance, the Hyphomytes is cultured to metabolize and partially decompose the hemicellulose.
The material obtained by the above method is expected to have various effects on human body. In the above method, however, since the plant fiber material is obtained by metabolization, a product with a stable quality cannot be obtained. The resultant product is not sufficient in production efficiency activity of the NK cells. In the above method, it takes much time to culture the Hyphomytes. This method is not always appropriate as an industrial manufacturing method.